New home sales posted an unexpected increase in September. Analysts viewed the small gain as highly questionable given the severe credit crunch that hit the housing industry this summer.

They predicted further sales declines before the worst housing slump in decades ends.

The Commerce Department reported Thursday that sales of new homes rose by 4.8 percent last month to a seasonally adjusted annual rate of 770,000 units. Economists had looked for a 2.5 percent decline.

But analysts noted that the increase came in a report in which the government revised the performance over the past three months sharply lower, showing that sales in August fell to an annual rate of just 735,000, the slowest pace in 11 years.

Even the September increase was viewed with skepticism.

All the strength came in the West, a region pounded by the credit crunch.

“This is definitely not a signal that the housing market is turning around,” said David Seiders, chief economist at the National Association of Home Builders. The group’s own survey of builder confidence fell to an all-time low in early October.

On Wall Street, stocks fell slightly. Worries about housing and the overall economy combined with another jump in oil prices to put traders in a pessimistic mood. The Dow Jones industrial average lost 3.33 points to close at 13,671.92.

Sales of new homes surged by 37.7 percent in the West, a highly suspect rebound given what was happening in the market for large loans. Sales rose 0.5 percent in the South but were down in the rest of the country, falling 19.5 percent in the Midwest and 6.6 percent in the Northeast.

Seiders said the pattern this year has been that the government substantially lowers its initial estimate of home sales once more complete data is gathered.

The National Association of Realtors reported Wednesday that sales of existing homes fell by a record 8 percent in September, a far more than expected.

Analysts said home sales are likely to fall for some time to come, with the housing market not stabilizing until inventories come under better control. That problem has been exacerbated by the rising number of homes going into default, which pushes more homes onto an already glutted market.

“We are expecting sales to continue to drop and not turn around until next year,” said Patrick Newport, a Global Insight economist.

The congressional Joint Economic Committee released a report Thursday estimating that 2 million subprime mortgages made to borrowers with weak credit could go into foreclosure over the next 18 months.